Touch screen, as an input medium, provides the user with better convenience than keyboards and mouse. Meanwhile, the pros and cons of its performance also directly impact on the consumer's actual experience.
At present, touch screens in the market are usually mutual-capacitance touch screens. The mutual-capacitance touch screen comprises a set of driving electrode lines and a set of probing electrode lines which intersect each other and are insulated from each other. When there are n (n denotes a natural number above 1) driving electrode lines and m (m denotes a natural number above 1) probing electrode lines, m+n electrode wirings need to be conductively connected to a flexible printed circuit board (abbreviated to FPC), respectively. The basic principle of the mutual-capacitance touch screen is: applying a voltage to the driving electrode lines, detecting change in signals of the probing electrode lines. The driving electrode lines determine the X-coordinate and the probing electrode lines determine the Y-coordinate. Upon detection, progressive scanning is performed for the driving electrode lines in the X-direction. At the time of scanning each row of driving electrode line, the signal on each probing electrode line is read. Through a round of scanning, the intersections of every rows and columns can be scanned, and m*n signals are scanned in all. Such detection manner can specifically determine the coordinates of multiple points, and can hence enable multipoint touch. The equivalent circuit model comprises, as shown in FIG. 1, a signal source 101, a driving electrode line resistor 103, a mutual capacitor 102 between the driving electrode line and the probing electrode line, a parasitic capacitor 104 between the driving electrode line, the probing electrode line and the common electrode layer, a probing electrode line resistor 105 and a detection circuit 106. When a finger touches, part of the current flows into the finger, which is equivalent to change in the mutual capacitance between the driving electrode line and the probing electrode line. By detecting the resulting tiny current change at a detection end, the coordinates of multiple points can be determined.
The prior art suffers from the deficiencies of poor positioning precision and low scanning frequency resulting from the touch detection using the above principle.